Evaluation of modulations in heart rate variability caused by a composition of herbal extracts.

The purpose of this prospective, placebo-controlled, randomized double-blind study was the examination of changes of the basic vegetative rhythms due to Cardiodoron, a composition of extracts of blossoms from Primula officinalis and Onopordon acanthium and from the herbs of Hyoscyamus niger. In its clinical use it is known as a modulating medicine in the treatment of functional disturbances of the cardiovascular system. With use of Holter monitoring, 24-h ECG recordings were obtained from 100 healthy subjects of whom 50 took the composition and 50 a placebo. Heart rate variability was evaluated from the 24-h ECGs by means of a power spectral analysis based on the Fast Fourier Transformation (FFT). Regulative influences on the rhythmic system due to the medicine were found. After four weeks of medication half of the verum group showed a tendency to an increased variability in the low and high frequency range at night (LFn: 0.04-0.15 Hz, HFn: 0.15-0.4 Hz) in contrast to the placebo group. The mean heart rate at night (HRn) showed a tendency towards a normalization in the verum group: in subjects with a low HRn the heart rate was increased and in subjects with a high HRn the heart rate was decreased. This effect could not be observed in the placebo group. After two further weeks without any medication this difference between verum and placebo was abolished.